The NY Times has an article about a study looking at whether HDL is truly protective against heart disease or whether it is just a sign. I’m glad to say that high HDL (the “good” cholesterol) is a sign of better heart disease risk–I’m glad to say that because I have fairly high HDL. The only question is whether the lowered risk of heart disease is caused by the higher HDL, or if the lowered risk for heart disease and the higher HDL are both byproducts of some yet unknown factor. In the study, they looked at genes that affected HDL level, and found that the genetic differences had no effect on risk. What this says to me is simply that they are not looking at the important genes, the ones that both lower heart disease risk and also raise HDL levels.
The question is important because pharmaceutical companies are now developing drugs to raise HDL, with the hope that this will lower heart attack risk in the same way that drugs that lower LDL levels lower heart attack risk.
At the end of the article there was an example of the unhelpful literalism that doctors sometimes display.
Dr. Kathiresan said there were many things HDL might indicate. “The number of factors that track with low HDL is a mile long,” he said. “Obesity, being sedentary, smoking, insulin resistance, having small LDL particles, having increased cholesterol in remnant particles, and having increased amounts of coagulation factors in the blood,” he said. “Our hypothesis is that much of the association may be due to these other factors.”
“I often see patients in the clinic with low HDL levels who ask how they can raise it,” Dr. Kathiresan said. “I tell them, ‘It means you are at increased risk but I don’t know if raising it will affect your risk.’ ”
When asked by patients with low HDL how they can increase their HDL levels, the doctor basically says “it may not help you,” instead of saying “you can increase your HDL by losing weight, exercising more, stopping smoking,” etc. All those things will increase the patient’s HDL and help him lower his risk.